The invention relates to a height-adjustable support device for supporting a load-bearing surface, e.g., for the seat of a chair, having a base and an upright tube disposed thereon vertically along a center axis, in which a height-adjustment element, e.g., a gas spring, is arranged. The height-adjustable element is rotatably and/or vertically displaceably guided by at least one guide surface disposed concentrically to the center axis of the upright tube and is supported on a support in the lower end section of the upright tube.